41
|
Describe the relation between Resonance
power and off resonance power.
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- The off resonance power = P / (
1 + Q2 )
Where P = Power at resonance
and Q = Tangent of the circuit
Phase angle
- The off resonance power is
reduced by factor ( 1 + Q2 ) to that of resonance power.
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42
|
Explain the following terms:
Impedance, Admittance, Conductance, Inductive reactive, Inductive susceptance,
Capacitive reactance and Capacitive
susceptance
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Impedance
( Z )
- It is defined as the combined
effect of resistance and (inductive or capacitive) reactance. Its unit is
ohm.
Z = r + j XL
OR
Z = r – j XC
Admittance
( Y )
- The reciprocal of impedance is
called as admittance. Its unit is Siemens.
Y = 1 / Z
Conductance
( G )
- The reciprocal of resistance is
called as conductance.
- Its unit is ohm-1.
G = 1 / R
Inductive
reactive ( XL )
- The opposition offered by the
inductance to the flow of current is called as inductive reactance.
- It is donated by XL
= 2πfL
Inductive Susceptance ( BL )
- The reciprocal of inductive
reactance is called as inductive susceptance.
- The inductive susceptance is
taken as negative because the inductive reactance is taken as positive.
BL=1 / XL
Capacitive
reactance ( XC )
- The opposition offered by the
inductance to the flow of current is called as inductive reactance.
- It is donated by XC
= 1 / 2πfC
Capacitive
susceptance ( BC )
- The reciprocal of capacitive
reactance is known as capacitive susceptance.
- The capacitive susceptance is
taken as positive because the capacitive reactance is taken as negative.
BC =1 / XC
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43
|
At which condition the
conductance is reciprocal of resistance and susceptance is reciprocal of
inductive reactance in the series RL circuit?
|
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Impedance
of series RL circuit
= R + jXL
= ( R + jXL ) / ( R2 + XL2
)
= [ R / ( R2 + XL2
)] + j [ XL / ( R2 + XL2 )]
= G + jB
Therefore
G = [ R / ( R2 + XL2
)]
B = [ XL / ( R2 + XL2
)]
- When the inductive reactance
becomes zero, the conductance is reciprocal of resistance.
- Similarly when the resistance
becomes zero, the susceptance is reciprocal of inductive reactance.
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44
|
Describe the condition for Parallel Resonance.
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Parallel Resonance
- The circuit is called as
parallel resonance when the net reactance of the circuit becomes zero.
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45
|
Define : Series Resonance Frequency
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Series Resonance Frequency
- It is frequency at which net
reactance of the circuit becomes zero.
fr = 1 / 2π √ ( LC )
|
46
|
Define : Parallel Resonance Frequency
|
|
Parallel Resonance Frequency
- It is frequency at which net
reactive component of the circuit becomes zero.
fr = √ [( 1 / LC ) –
( R2 / L2 )]
|
47
|
Give reason : The parallel
resonance circuit is called as rejector circuit.
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Rejector circuit
- The parallel resonance circuit
is called as rejector circuit because it rejects that frequency with it
resonates.
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48
|
Give reason : The parallel
resonance is also referred as current resonance.
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Current Resonance
- The parallel resonance is
called as current resonance because current circulates between two parallel
branches is much higher than the supply current.
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49
|
Describe the effect of
frequency on the susceptance of the parallel resonance circuit.
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|
Capacitive Susceptance
- It is directly proportional to the
applied frequency. As the frequency increases, the capacitive susceptance
increases.
Inductive Susceptance
- It is inversely proportional to
the applied frequency. As the frequency increases, the inductive susceptance
decreases.
|
50
|
Explain the term : Q factor of
parallel circuit
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Q factor of Parallel circuit
- It is defined as the current
circulating between two parallel branches to the supply current.
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51
|
Describe the significance of Q
factor in the series resonance circuit and parallel resonance circuit.
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|
Significance
of Q factor
- The Q factor in the series
resonance indicates voltage magnification whereas it indicates current
magnification in the parallel resonance circuit.
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